[rollei_list] Re: OT Ancient Computers (was Re: Re: Rollei -Singapore) now analogue versus digital
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Mon, 12 Jan 2009 14:26:20 -0800
----- Original Message -----
From: "Frank Dernie" <Frank.Dernie@xxxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, January 12, 2009 7:38 AM
Subject: [rollei_list] Re: OT Ancient Computers (was Re: Re:
Rollei -Singapore) now analogue versus digital
The fact that several (no more) prominent people still use
film is not evidence that it is better.
In all practical ways digital has exceeded the capability
of film for some time. Certainly if there is an effect
which one wishes to achieve, using a vintage LF lens for
example, film may have to be the choice but that does not
make film better, just an appropriate choice in some
circumstances.
Analogue sound is the same. The fact that some people
prefer the sound of analogue is not evidence that it is
better (I am one by the way) but that it matches their
taste in sound. My Mum likes her old valve (tube) radio -
"lovely tone" and it does sound nice, but there are no
high frequencies at all, along the same lines as LPs in
real world systems but more extreme.
When Meridian, the digital specialists, were looking at
the frequency and amplitude of the "music data" on LP
records the -highest- dynamic range they found was
equivalent to 11-bit IIRC, though many "experts"
attribute the inferiority of digital as they hear it to
the inadequacy of 16 bit recording, which it almost
certainly can't be. The shortcoming of the 44.1kHz
sampling frequency is a different story in real
engineering implementation though.
I designed high end HiFi equipment for a while. I have
never seen so many ridiculous pseudo-technological
explanations for real phenomena in any other field of
work I have done.
cheers,
Frank
In the long ago I did a lot of custom recording. At the
time we used mostly 15 IPS tape, mostly on Studer machines
with Dolby A. As a back-up we began to use a Sony digital
adaptor running on a VTR. This was an early device and had
problems but worked pretty well. The general opinion was
that the digital recordings sounded "harsh" compared to the
tape. However, what I found was that digital sounded more
like what I heard in the monitors during recording, the
harshness came from the microphones being used and their
positions. Both mics and techniques had evolved to overcome
the mushiness of tape.
Disc recoding has a set of vices all its own. Among them
are some inherent distortions which are very hard to reduce
plus the fact that the "scanning" errors become worse toward
the inside grooves due to the reduced goove velocity. Oval
rather than round needles help reduce scanning errors at all
speeds but still can not completely overcome the odd order
harmonic distortion of the system. Typical disc systems have
harmonic distortion on the order of a few percent and can
have lots of intermodulation distortion. Analogue tape
recording using biased direct recording has other types of
distortion plus the lateral print effect that causes loss of
high frequencies over time, especially the first few hours
after a recording has been made.
Digital has none of these plus it has absolute timing,
meaning no flutter or wow. The greatest problem with digital
as it is practiced is that the sampling frequency was chosen
to accomodate the bandwidth limits of what is now very old
analogue recording technology. The problem comes not from
the sampling frequency itself but rather the anti-aliasing
filters. Because the sampling rate is close to the Nyquist
minimum the filters must of necessity be very sharp which
can cause all sorts of problems with phase shifts and
ringing. Raising the sampling frequency would probably
eliminate this completely.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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